// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_SOCKET_SOCKET_PERFORMANCE_WATCHER_H_
#define NET_SOCKET_SOCKET_PERFORMANCE_WATCHER_H_

#include "net/base/net_export.h"

namespace base {
class TimeDelta;
} // namespace base

namespace net {

// SocketPerformanceWatcher is the base class for recording and aggregating
// per-socket statistics. SocketPerformanceWatcher must be used on a single
// thread.
class NET_EXPORT_PRIVATE SocketPerformanceWatcher {
public:
    virtual ~SocketPerformanceWatcher() { }

    // Returns true if |this| SocketPerformanceWatcher is interested in receiving
    // an updated RTT estimate (via OnUpdatedRTTAvailable).
    virtual bool ShouldNotifyUpdatedRTT() const = 0;

    // Notifies |this| SocketPerformanceWatcher of updated transport layer RTT
    // from this device to the remote transport layer endpoint. This method is
    // called immediately after the observation is made, hence no timestamp.
    // There is no guarantee that OnUpdatedRTTAvailable will be called every time
    // an updated RTT is available as the socket may throttle the
    // OnUpdatedRTTAvailable call for various reasons, including performance.
    virtual void OnUpdatedRTTAvailable(const base::TimeDelta& rtt) = 0;

    // Notifies that |this| watcher will be reused to watch a socket that belongs
    // to a different transport layer connection. Note: The new connection shares
    // the same protocol as the previously watched socket.
    virtual void OnConnectionChanged() = 0;
};

} // namespace net

#endif // NET_SOCKET_SOCKET_PERFORMANCE_WATCHER_H_
